The present application is generally directed to a method of making polysilsesquioxane and organohydridosilane compounds and, more particularly, to a base-catalyzed, disproportionation method of making polysilsesquioxane and organohydridosilane compounds.
Organopolysilsesquioxanes have applications as material for low-K dielectrics, ceramic precursors and photoresists. Organohydridosilane compounds have applications in the electronic and semiconductor fields to coat silicon chips and other components, serving as protective coatings and interlevel dielectric layers.
Polysilsesquioxane compounds can be produced by hydrolytic condensation of a silane in an aqueous solution of ammonia or an amine. However, organohydridosilanes are not produced (Kimura, U.S. Pat. No. 4,528,390).
Polysilsesquioxanes can also be made using a sol-gel synthesis method involving the hydrolysis of some organotricholorosilanes or organotrialkoxysilanes in the presence of acid or base catalysts and organic solvents. However, under sol-gel conditions most organotrialkoxysilanes do not afford silsesquioxane gels. This limits the range of organic functionalities that can be introduced into these hybrid organic-inorganic materials. This polymerization process also requires solvent and stoichiometric water and produces alcohol and water condensation by-products.
In an alternative route to polysilisesquioxanes, catalytic disproportionation, by titanium complexes, of linear or cyclic oligomers of methylhydridosiloxanes have produced polymethylsilsesquioxanes (R. Laine, J. Rahn, K. Youngdahl, F. Babonneau, M. Hoppe, Z. Zhang, and J. Harrod, Chem. Mater., 1990, 2, 464-472). This process requires inert conditions because of the moisture and air sensitivity of the titanium catalyst. Redistristribution reactions of alkoxy-and siloxysilanes have also been demonstrated using dimethyltitanocene catalysts (S. Xin, C. Aitken, J. Harrod, Y. Mu, and E. Samuel, Can. J. Chem, 1990, 68, 471-476).
Hydridosiloxanes and organohydridosiloxanes can be produced by catalyzing the hydrolysis and condensation of a silane monomer, where the silane monomer is contacted with a phase transfer catalyst in the presence of a reaction mixture comprising a nonpolar or polar solvent (Hacker et al., U.S. Pat. No. 6,043,330).